Inclusion Criteria Prospera Arm:

1. 18 years of age or older
2. Renal allograft (kidney transplant) up to 2 years prior to signing informed consent. Newly transplanted patients to receive Prospera testing within 60 days of transplant
3. A genetically different donor (not an identical twin)
4. Selected by a healthcare provider to receive Prospera dd-cfDNA test according to the regular interval testing schedule as part of their practical care
5. Able to read, understand and provide written informed consent
6. Willing and able to comply with the study visit schedule and study requirements

Exclusion Criteria Prospera Arm:

1. Pregnant
2. Routine ongoing testing with another dd-cfDNA or RNA biomarker test after enrollment into the ProActive study. Receipt of another dd-cfDNA test within 30 days of a patient being enrolled in the study.
3. History of another organ transplant (i.e. aside from renal allograph)
4. A serious medical condition that may adversely affect ability to participate in the study (e.g, dementia, current diagnosis of cancer)
5. Previously enrolled in the ProActive Registry, with the exception of a graft failure and a new renal allograft

Inclusion Criteria Control Arm:

1. 18 years of age or older at the time of transplant
2. Had a renal allograft
3. Had a genetically different donor
4. Had a minimum of three evaluations per year during the three years since the renal allograft or until allograft failure

Exclusion Criteria Control Arm:

1. Female patients who were pregnant at any time during the 3-year historical control data collection period
2. Had a transplanted organ other than kidney
3. Received results from a dd-cfDNA test designed to assess renal allograft rejection during the historical control data collection period